The present invention relates to a magnetic disk apparatus and particularly to a magnetic disk apparatus with an improved reliability when operated for a long time.
For increasing the recording density of a magnetic disk apparatus, it has been so far a problem to narrow the distance between a magnetic disk (which will be hereinafter referred to merely as xe2x80x9cdiskxe2x80x9d) and a magnetic head (which will be hereinafter referred to merely as xe2x80x9cheadxe2x80x9d), and many attempts have been made to lower the head flying height, make the protective overcoat formed on the head and the disk thinner, make the lubricant layer on the disk protective overcoat thinner, etc. For high speed recording or reproduction of magnetically recordable or recorded information, it has been attempted to make the disk revolution speed higher.
However, the lowering of the head flying height leads to an increase in the contact frequency between the head and the disk, ultimately to decomposition of the lubricant on the disk, wearing of the protective overcoat formed on the head and the disk, or the like, thereby considerably lowering the reliability of the magnetic disk apparatus. It is also known that the lubricant on the disk is gradually decreased by high speed revolution of the disk besides the vanishing thereof by contact with the head.
To make up for the vanished lubricant on the disk by contact with the head or for the decreased lubricant by revolution of the disk, JP-A-2-37589 and JP-A-7-73659, U.S. Pat. Nos. 4,626,941, 4,789,913, 5,138,506, 5,331,487 and 6,031,685 disclose a means of supplying a lubricant. Near-contact recording by intermittent contact of the head with the disk or contact recording by continuous contact of the head with the disk will be hereafter key technical items for further improvement of recording density, where such means of supplying a lubricant will be an essential technical item.
It is also known that in the magnetic disk apparatus some kinds of gas components adsorbed on the head or the disk undergo chemical reactions by heat, etc. generated by contact of the head with the disk, thereby forming debris between the head and the disk. Such debris formation will give fluctuations to the head flying height and will increase the contact frequency between the head and the disk, thereby erasing the recorded information on the disk or crashing the head or the disk in the worst case, or increasing the head flying height and then leading to a failure in magnetic recording or reproduction of information on the disk in some case. Indeed, in the case of increasing the contact frequency between the head and the disk due to the lowering of head flying height, a probability of trouble occurrence will be increased. Trouble-causing gas components are those outgassing from the structural members of the magnetic disk apparatus in most cases, but in some case are impurities from the process steps during the production or from the surrounding atmosphere after the production.
Various methods for reducing trouble-causing compounds on the head-disk interface (HDI) have been so far proposed (such compounds will be hereinafter referred to as xe2x80x9ccontaminantsxe2x80x9d): for example, a method of abating the contaminant by degassifying the structural members of a magnetic disk by heating, a method of removing the contaminants by adsorption by providing the apparatus with a gas adsorbent, as disclosed in JP-A-60-219695, a method of catalytically removing the contaminants by polymerization, as disclosed in JP-a-6-76556, a method of removing the trouble-causing contaminants by chemisorption by providing a magnetic disk apparatus with some kind of metals, as disclosed in JP-A-6-36548 and JP-A-6-302178. However, these methods have been found not satisfactory yet.
An object of the present invention is to provide a magnetic disk apparatus capable of preventing contaminant-causing troubles from occurrences, and improving the reliability of the apparatus when operated for a long time.
The present invention provides a magnetic disk apparatus, which comprises a casing, and at least a magnetic medium for recording information, a magnetic head for recording and reproducing magnetic information on the magnetic medium and a mechanism of driving the magnetic medium and the magnetic head, each provided in the casing, where at least one of monofunctional compounds is provided in the gas phase in the casing.